fehling



Jan. 31, 1956 H. R. FEHLING 2,732,329

INK RESERVQIR TUBE 'Filed sept. 22, 1949 2 Sheets-sheen'v 2 H66. 2'ff/6.2 2

Attornev:

`to the -usual size of a writing instrument.

INK REsERvoIR TUBE :Hans Reinhard Fehling,London, England, assigner to,Compania Uruguaya `de yFomento Industrial S. A., yMontevideo, Uruguay,Southv America `This invention relates to-Ameans for arresting orpreventing the liow of a liquid from an open ended tube or Y the likeand has particular but not exclusive reference to ink reservoirs usedfor writing instruments of the ball tip type.

Instruments of this type arenow well known; there is, for example, theball tip type of instrument sold under lthe trademark Biro, and coveredby such inventions described in U. S. Patent 2,397,229, filed March 26,1946, and U. S. Patent 2,416,896, led March 4, 1947, and the specicationof copending patent application Serial Number 657,597,1iled March 27,1946, `now abandoned, which describe instruments of thesaid type.

Several diiferent constructions oit ink reservoir are satisfactory foruse with writing instruments of this type amongst which the followingmay be mentioned by `way of example.

,consumed is described in copending application Serial -Number 104,242,filed July 12, 1949, now'Patent Number 2,672,127.

Yet a further modilication of ink reservoir has been 'described in whichthe ink reservoir is constituted by a tube which at one end communicateswith the bail but which at the other end has ,a layer of a liquid moreviscous than the ink. It will be appreciated that with all openended-tubes containing liquids there is a slight tendency for the liquidto run out, by what is usually known as creep If the inner surface ofthe tube has any imperfections such as an axial scratch, the liquidtends to creep along such scratch; a small scratch is, in eiiect a tinebore duct and the ink is drawn therealong bycapillary action. Othercauses of liquid creep are small errors in manufacture of the tube orfaulty handling while in use.

It is an object of the present invention to prevent or arrest the ow ofa liquid from an open ended tube.

if the internal diameter of the ink reservoir is not more than 2.5 mm.the meniscus formed in the ink column at the end remote from the ball isso strong that under normal conditions of use intemperate latitudes, itwill not break and the ink will not creep out of the open end. Thevolume of ink in a reservoir of "2.5 mm. internal diameter is however,necessarily limited having regard lf the internal diameter of thereservoir is increased beyond 2.5 mm. internal diameter to atord alarger volume of inlcth'e risk of breakage of said meniscus or inkcreepage is increased. The present invention resides, ltherefore, -in

`the provision of means for "arresting for preventing the *llow of aliquid-from aveuted-tubef-or thef-like, Vwhich 2,732,829 Patented Jan.31, 1956 2 consists in the provision of at least one peripheral andcontinuous or substantially continuous step or groove formed on or inthe inner surface of said tube and located at any convenient positionbetween the said vent and that end of the column of liquid adjacentthereto in the `said tube when the tube is charged with said liquid, the

said step or groovebeing so arranged as to ai'ord a sharp change indirection of movement to uid tending to llow axially relatively thereto.In carrying the invention into effect it is preferred toprovide morethan one of the said steps or grooves, all of which are separated fromeach other; they may be separated by a ridge or the like.

It will be readily appreciated that the prevention of ink creep inwriting instruments ofthe type specified is one of considerableimportance. -If a user of such an instrument touches the end of an inkreservoir in which creep has occurred, he will get ink on his hands; astate of affairs to be avoided. It is, therefore, a specific object ofthe present invention to prevent or arrest the flow of ink from inkreservoirs of writing instruments of the type speciiied by utilising avented tube having the characteristics set out in the last precedingparagraph.

Any suitable ink may be employed in writing instruments of the typespecied; examples of suitable inks are disclosed in co-pending patentapplications Seiial Number 657,598, liled March 27, 1946, and SerialNumber 659,149, led April 2, 1946, both -now abandoned.

In order that the invention may be more readily Vunderstood referencewill now be made to the accompanying drawings in which:

Figure 1 shows (mainly in cross section and by way of example) areservoir writing instrument of the type specified according to theinvention.

`Figure 2 is a diagrammatic View of an ink reservoir according to thisinvention.

Figure is an alternative construction to Figure 2.

Figure 4 Vis another alternative construction of Figure 2.

Figure 5 is a detailed View of a split ring.

Figs. 6 and 7 show partly sectional, fragmental Views of embodiments ofthis invention.

The instrument shown in Figure'l comprises a writing extremity 1 whichhouses a ball 2 and is connected to a tubular reservoir 3. Thisreservoir communicates with the gap between the ball and its housing bymeans of a'srnall-diameter feed duct. The said gap and feed duct are notillustrated since they are well understood by these familiar with theconstruction of writing instruments of the type specified. It may bementioned, however, that the ball is desirably in the order of 1 mm. indiameter, the diameter of the feed duct at that end thereof whichcommunicates with the ball housing is less than that of the ball, andthe width of the gap is preferably between 1 104 and l l03 cms.

The unit consisting of the Writing extremity ll and the reservoir 3, ishoused in a casing consisting of a barrel 4 provided with an air hole 5and an adaptor 6. Conveniently, but not necessarily, the writingextremity is screwed into the adaptor 6 at 7 and said adaptor and barrelare screwed together at 8. A cap, not shown, may be provided which whenthe instrument is not in use, ts over a ring in the casing at 13 toprotect the Writing extremity and which, when the instrument is in use,is fitted over the other end of said instrument.

It will be observed that the rear end 9 (i. e. that end which is remotefrom the ball 2) of the tubular reservoir 3 is open so that the contentsof the reservoir are exposed to atmospheric pressure at this end.

The ink constituting the writing fluid is shown at 10. The ink columnforms a continuous vein of liquidexball and -its housing.

A recess groove or channel, located inside the reservoir 3, isillustrated at 12. This groove or channel is formed as a ring inside thereservoir so that it is between the meniscus 11 and the open end of thereservoir 9. The ring provides a step over which the lm of ink must ow.

In Figure 2 the ink column 10 is shown surmounted by a layer of anotherliquid 14 more viscous than the ink. In this specific example twogrooves 15 and 16 of square cross section are shown situated between theviscous liquid 14 and the open end of the tube 9.

In Figure 3 a piston or float 17 is shown resting on the top of the inkcolumn l0. In this example the grooves 18 and 19 are shown separatedfrom each other by a sharp ridge 20. These grooves may be adjacent toeach other as shown, or they may be of a certain distance from oneanother. The end of the reservoir is closed but the contents of thereservoir are maintained at atmospheric pressure by means of the smallair vent 21.

An alternative constructional method of carrying the invention intoeffect is shown in Figure 4 which shows the rear end of an ink reservoirsimilar to that shown in Figure 2.

The grooves formed in the inside of the reservoir of Figure 2 arereplaced by removable rings 23. A more detailed view of one of theserings is shown in Figure from which it will be seen that the ring 23 isa noncontinuous ring having a gap 26; formed in the inside of the ringis a V-shaped groove 22 having comparatively sharp edges 27 and 28. Thering is preferably of resilient material of such a size that when thering is compressed so that the gap Z6 is closed (i. e. the two faces 24and 25 separated by the gap 26 are in contact) the maximum diameter ofthe ring is the same as the internal diameter of the ink reservoir. Therings are pushed into the reservoir from the open end 9.and in Figure 4it will be seen that two rings are provided with a short space 29between them; preferably the gaps 26 are not in line with one another.Not only will the groove 22 in the rings act as a reservoir for any inkwhich may creep but also the gap 2g formed between the walls of the tworings 23 will also function as an ink reservoir. in these specicexamples the cross sectional shape of the grooves or channels is squareor V-shaped. It will be appreciated that any suitable cross sectionalshape may be used but it is preferable to use a shape which will leave acomparatively sharp edge both for entering and leaving the groove whenapproached in a direction along the axis of the reservoir. The reasonfor the sharp edge is simply explained. When a liquid lm is creeping itssurface tension will resist any tendency to a sudden change ofdirection, because in order to move over an edge the iilm surface has tobe strongly curved. Such a curvature can only be produced if the liquidat this point is at a pressure higher than atmospheric. Such a highpressure can only be produced by force of gravity (in which case theliquid must first accumulate) or by shocks or the like. It is therefore,apparent that it is more important that the edge is sharp in the sensethat the radius of curvature at this point is as small as possible.

The groove also acts as a reservoir for any creeping liquid. As theliquid creeps into the grooves the groove itself acts as a capillaryreservoir thus causing the liquid to fill up the groove before trying toescape therefrom; by providing a plurality of grooves the total capacityis of course increased.

lt may be said that usually the total volume of ink which creeps duringthe life of one of these ink reservoirs (that is before all the ink inthe reservoir is consumed by usage), is comparatively small. The inkcapacity of one of the grooves according to this invention is very smallcompared with that of the ink reservoir, but is in general sufficient toaccommodate the volume of ink which creeps.

Referring now to the constructions illustrated in Figures 6 and 7 itwill be seen that in the construction shown in Figure 6 there are formedon the interior surface of the reservoir 3 a series of steps 30 each ofwhich is normal to the longitudinal axis of the reservoir. In theconstruction shown in Figure 7 each step 30 has an obtuse angle to saidaxis. The ink column is represented at 3.9. the open mouth of thereservoir its flow is arrested by each step in turn for the reason thatthe ink, due to surface tension, exhibits a reluctance to eiect aviolent change of direction in the ow. The number of steps may be variedas desired but in practice it is found that two or three are adequate toprevent ink owing out of the open mouth of the reservoir. A groove mayof course be provided at the base of each step but the essentialinhibition to ink creepage is the step itself and the advantage of theconstructions illustrated in the embodiments shown in Figures 6 and 7 isthat they can readily be produced by a moulding process and do notnecessitate a separate operation such as is entailed in the formation ofgrooves after the tube has been produced.

It will be appreciated that in all the constructions illustrated hereinthe steps and grooves are so arranged that if a film of liquid attemptsto ilow axially relatively thereto such lm will of necessity assume amarked degree of convexity over the sharp edge of the step or groove andit is this phenomenon which functions to arrest the ow.

While preferred embodiments of the invention have been disclosed toadvantage, it is understood that modifications as to the Aarrangementand use of parts may be made without departing from the spirit and scopeof the invention as claimed.

I claim:

l. A vented tube intended for the reception of a viscous liquid andsuitable for use as an ink reservoir in writing instruments of the typehaving at least one peripheral and continuous step between the vent andthe adjacent end of the liquid column, when the tube is charged withsuch liquid, said step providing a sharp angle on the inner surface ofsaid tube and located intermediate said vent and that end of the columnof liquid adjacent thereto in said tube when said tube is charged withsaid liquid, said step providing a passage of substantially similardiametric dimension as the inside diameter of said tube and in directcoaxial communication with the inner surface of said tube therebyaifording a sharp angular change in direction of movement to fluidtending to iiow axially relative thereto, the bore of the reservoir oneither side of said step for preventing the flow of ink beingsubstantially the same.

2. A vented tube intended for the reception of a viscous liquid andsuitable for use as an ink reservoir in writing instruments of the typehaving between the vent and the adjacent end of the liquid column whenthe tube is charged with such liquid, a plurality of spaced peripheraland continuous steps formed in the inner surface of said tube, saidsteps being of successively wider area and located away from thelongitudinal axis of said tube and disposed intermediate said vent andthat end of the column of liquid adjacent thereto in said tube when saidtube is charged with said liquid, thereby affording a sharp angularchange in direction of movement to fluid tending to flow axiallyrelative thereto.

3. A vented ink reservoir tube for a writing instrument having means forarresting or preventing the ow of ink from said vented tube, said meanscomprising a portion provided with a peripheral and substantiallycontinuous recess formed along the inner surface of said tube, saidrecess being sharp-edged on the side of the column of ink to prevent theow of ink into said recess, said recess being disposed intermediate saidvent and the end of the column of liquid adjacent thereto in said tubewhen said tube is charged with said liquid, said recess beingsubstantially coaxial with said tube and providing a passage ofsubstantially similar diametric` dimension as the lf for any reason saidink tends to creep towardsinside diameter of said tube and in directcoaxial communication with the unrecessed inner surfaces of said tubethereby providing a sharp change in the direction of movement of lluidtending to flow axially relative thereto.

4. The combination according to claim 3, wherein said means is providedwith a plurality of peripheral continuous recesses.

5. An ink reservoir tube for accommodating a column of ink therein foruse in a ball point writing instrument having a vent for the admissionof air and means for preventing creep of a film of ink along theinterior surface of the tube towards said vent, said means comprising atleast one peripherally continuous sharp-edged portion along the interiorsurface of said tube providing a passage in direct coaxial communicationwith the inside of said tube and of substantially similar diametricdimension as the inside diameter of said tube, the sharp edge beinglocated on the side of the column of ink to prevent the ow of ink intosaid passage.

i 6. A tube according to claim in which said means is constituted by aring inserted into the body of the tube.

7. A tube according to claim 6 in which the ring or each thereof is asplit ring so arranged and designed that when inserted into the tube thering is substantially closed and forms a sharp recessed edge to abruptlychange the creepage of the ink in said tube toward the open end thereof.

8. An ink reservoir tube for accommodating a column of ink therein foruse in a ball point writing instrument, said tube being provided with avent for the admission of air as the ink is used up in writing, andmeans for hindering creep of a film of ink along the surface of saidtube towards said vent, said means consisting of at least one abruptsharp-edged peripheral steplike portion of substantially uniform widthin the interior of said tube at a location inwardly of said vent, saidstep-like portion providing a passage of a diametric dimension at leastas large as the inside diameter of said tube in direct substantialcoaxial communication with the inside of said tube and presenting asharp edge on the side of said steplike portion adjacent the column ofink to prevent the How of ink into said passage, the sharp edgeextending completely around the interior of said tube and with at leasta part thereof away from the longitudinal axis of said tube.

References Cited in the tile of this patent UNITED STATES PATENTS682,574 Skilton Sept. 10, 1901 2,087,139 Cameron July 13, 1937 2,435,123Biro Ian. 27, 1948 2,452,504 Teift Oct. 26, 1948 2,500,998 Morris Mar.21, 1950 2,504,649 Chesler Apr. 18, 1950 2,519,635 Claret Aug. 22, 1950FOREIGN PATENTS 571,698 Great Britain Sept. 5, 1945 582,186 GreatBritain Nov. 7, 1946 254,826 Switzerland Jan. 3, 1949

